1. Field of Invention
This invention relates to a safety mechanism for a plasma torch cutter.
2. Brief History Of The Prior Art
A plasma torch metal cutter generates substantial voltage in creating a very high metal cutting heat whereby the apparatus is a source of peril unless carefully safeguarded and armed against inadvertent use at a time when all parts are not present and in their proper place.
In the Hatch U.S. Pat. 4,701,590, a torch is provided with a spring loaded mechanism to expel an electrode and break the circuitry thereof to prevent its operation in the event of a missing part.
In Hatch U.S. Pat. No. 4,691,094, a sliding gas valve closes off the gas flow when any necessary part is not in place.
In Wilkins U.S. Pat. No. 4,585,921 there is present a predetermined measurement of the resistance between the torch tip and the workpiece and that between a person's hand to ground and if the latter resistance is below the predetermined resistance, the torch will not operate.
In Carkhuff U.S. Pat. No. 4,580,032, a safety control responds to the partial removal of a heat shield to interrupt the flow of gas and a responsive switch shuts off the gas.
It is desirable to provide a positive acting means which serves to not complete an energizing circuit unless certain essential parts which may readily and inadvertently be omitted are in fact in operating position.